JPH04297411A - Silk pigment adsorbing colloidal titanium oxide and its production - Google Patents

Abstract

PURPOSE:To obtain a silk pigment, excellent in ultraviolet ray shielding effects and further improved in adhesion to skin, extensibility, touch, masking properties, dispersibility, miscibility; balance between hydrophilicity/lipophilicity, perspiration preventive and skin protective properties and extremely useful for cosmetic, foods and coatings. CONSTITUTION:A titanium oxide sol is mixed with an aqueous solution of silk fibroin prepared by dissolving silk fiber and a pigment of a different kind is further mixed therewith or the solution without mixing thereof is subsequently subjected to one or more treatments selected from mixing of a coagulable salt, blowing of air, coagulation at the isoelectric point, ultrasonic treatment, stirring at a high shearing deformation rate, etc., to coagulate and deposit particles. The resultant mixture solution is then washed with water, dried and pulverized to industrially and advantageously afford a silk pigment in which colloidal titanium oxide is adsorbed on a compound pigment of silk powder that is a substrate pigment with the pigment of the different kind. The above- mentioned silk pigment has the aforementioned effects.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a silk pigment in which colloidal titanium oxide is adsorbed to silk powder or a composite pigment of a different pigment and silk powder, and the production thereof. Regarding the law. More specifically, the present invention relates to a colloidal titanium oxide-adsorbing silk pigment with excellent ultraviolet shielding effects and a method for producing the same.

0002

[Prior Art] Regenerated protein fine powder, especially regenerated silk fibroin powder, has appropriate hygroscopicity and moisturizing properties, excellent affinity for the skin, good hydrophilicity-lipophilic balance, and even a slight amount of ultraviolet absorption. It has the following characteristics and has traditionally been mainly added to makeup cosmetic bases (Japanese Patent Publication No. 58-38449). In addition, the present inventors utilized the above-mentioned favorable properties of silk fibroin to improve adhesion, extensibility, dispersibility, and miscibility by substantially covering the particle surface of common pigments with a regenerated silk fibroin film. Patent Publication No. 57-115 for pigments for paints and cosmetics that have outstanding properties such as properties, coating properties, oil absorption properties, balance between hydrophilicity and lipophilicity, antiperspirant properties, feel, skin protection properties, dyeability, etc., and a method for producing the same.
No. 77 (silk coat pigment).

[0003] In recent years, as paints and cosmetics have become more sophisticated, the conventional general functions of pigments are no longer sufficient, and a wider range of sophisticated so-called high functions are required. The reality is that these functions alone are no longer sufficient. One way to improve the functionality of pigments is to combine them with highly functional ingredients, and in this case, one of the challenges that is widely required is to provide pigments with a high degree of UV-shielding effect. be. As a method of imparting ultraviolet shielding effect to pigments, there is a method of coating ultraviolet absorbers, or a method of coating pigments with ultrafine particles with a diameter of 10 to 1000 m.
A method of mixing powders of μ (particle size) is well known. on the other hand,
When mixing ultrafine particles with a particle size of 10 to 1000 mμ (particle size) for the purpose of ultraviolet shielding, if they are in powder form, the smoothness on the application surface such as the skin will be poor, and if mixed with other pigments. It also has poor properties, and there are various problems when producing a uniform mixed powder.

[0004] Furthermore, oil-based agents are generally used as ultraviolet absorbers in order to avoid elution and caking due to water or sweat. Conventionally, the method for treating oily pigments is to dilute the oily body with an appropriate solvent to about the same amount as the treated pigment, mix and suspend the pigment therein, and then distill off the solvent while stirring. It is true. However, in this method, since the oily substance is merely attached to the surface of the pigment particles, there is a problem that only a very small amount of the oily substance can be mixed with the pigment. In other words, in the case of a method that involves simply adhering to the pigment surface, the oily substance on the pigment surface acts as a binder as the solvent is distilled off, and if the amount of oily substance is large, the final product obtained is a pigment in the form of lumps. It is in a state where it hardens and is very prone to caking. For this reason, in conventional methods, the amount of oily material is limited to at most 1 to 2% by weight based on the pigment. In addition, conventional methods require environmental measures because they use solvents, require explosion-proof equipment, require solvent recovery and purification equipment, and have the disadvantage that the equipment is too large for the production volume. Ta. Furthermore, even when the amount of oily substance is limited to 1 to 2% by weight or less based on the pigment, the resulting product is often used as a base for cosmetics due to its adhesive properties and
It has poor functions such as extensibility, dispersibility, and miscibility, and has had various problems in use, such as not being able to be blended in large amounts.

[0005] As a method to solve these problems, the present inventors first made a regenerated protein in the form of a fine powder or a regenerated protein containing a base pigment, and an oily substance was formed inside the fine powder in the form of minute droplets. A proposal was made regarding a fine powder of dispersed and incorporated oily body storage and regeneration protein (Japanese Unexamined Patent Publication No. 62-250056).

[0006] In addition, a technique in which colloidal gold hydrosol is easily adsorbed to silk and applied to gold dyeing of silk fabrics and silk powder is disclosed in Japanese Patent Application Laid-Open No. 62-299587 and Japanese Patent Application No. 1998.
Furthermore, the present inventors have proposed a method of mixing gold hydrosol into an aqueous silk fibroin solution and performing gold staining in the state of silk fibroin microgel (Japanese Patent Application No. 201776/1999). issue). The present inventors have discovered that titanium oxide sol, like gold hydrosol, is easily adsorbed onto silk powder at a high yield and has completed the present invention.

[0007]

[Problems to be Solved by the Invention] The present invention improves the drawbacks of the prior art, and its purpose is to contain colloidal titanium oxide in the form of ultrafine particles that have a highly functional ultraviolet shielding effect. It has an excellent UV shielding effect, and has excellent adhesion to the skin, extensibility, and feel.It also has excellent hiding properties, dispersibility, miscibility, balance of hydrophilicity and lipophilicity, antiperspirant properties, feel, and skin protection properties. The object of the present invention is to provide a fine powder that is extremely useful for cosmetics, food, and paints, and to provide an industrially advantageous method for producing the same.

[0008]

[Means for Solving the Problems] In order to achieve the above object, the present invention takes the following configuration. That is, the present invention relates to a silk pigment characterized in that colloidal titanium oxide is adsorbed to a base pigment of silk powder or a composite pigment of silk powder and a different pigment.
The method of the present invention involves mixing a titanium oxide sol with an aqueous silk fibroin solution obtained by dissolving silk fibers, and then mixing a coagulating salt with or without mixing a different pigment.
It is characterized in that the particles are coagulated and precipitated by at least one treatment such as air blowing, isoelectric focusing, ultrasonic treatment, and stirring at a high shear deformation rate, followed by washing with water, drying, and pulverization.

The constituent elements of the present invention will be explained in detail below. The colloidal titanium oxide-adsorbed silk pigment of the present invention has colloidal titanium oxide adsorbed to silk powder or a composite pigment of silk powder and a different pigment, and in the present invention, both are collectively referred to as silk pigments.

The silk powder of the present invention is regenerated silk fibroin, and at least 50% by weight, preferably at least 90% by weight, is composed of hot water-insoluble fibroin (β-type structure). If it is less than 50% by weight, the hydrophilicity of fibroin becomes extremely strong, causing adhesion and caking with water and sweat, causing the powder particles to become secondary particles (particles aggregate to form giant particles), and the aqueous dispersion medium ( Dispersibility tends to decrease in water-based paints and cosmetics) and oil dispersion media (oil-based paints and cosmetics). Also, the spreadability and feel during application become worse. The above-mentioned hot water-insoluble fibroin is
It is called fibroin that does not dissolve even after 5 minutes of boiling. In the hot water-insoluble silk fibroin, the intermolecular hydrogen bonds of the fibroin are substantially in the β structure. The proportion of hot water insolubility of regenerated silk fibroin can be set within a predetermined range by selecting the regeneration method from an aqueous solution.

[0011] The different pigments used in the present invention are a general term for white pigments for paints or cosmetics, extender pigments, pearl pigments, etc., such as talc, kaolin, mica, titanium oxide, zinc oxide, mica titanium, etc. , calcium carbonate, magnesium carbonate, zinc stearate, magnesium stearate, magnesium silicate, organic pigments, and composites thereof, which may be used singly or in combination of two or more. The average particle size of the different pigments is usually 0.08 to 20 microns. In the present invention, the amount of different pigments to be combined is 0 to 80% (by weight) of the silk pigment, more preferably 0 to 70% (by weight).
%. If it exceeds 80%, the proportion of silk in the silk composite pigment will be small, and the amount of colloidal titanium oxide adsorbed will be extremely small, making it impractical.

[0012] In the present invention, the titanium oxide sol to be adsorbed onto the silk powder or the composite pigment of silk powder and a different pigment may be one produced by a known method. That is, a method of hydrolyzing a titanic acid aqueous solution to produce metatitanic acid, neutralizing and washing it, and peptizing the resulting gel with an acid, a method of deionizing a titanic acid aqueous solution with an ion exchange resin, or Examples include a method in which hydrogen peroxide is added to a gel or sol of hydrous titanic acid to dissolve the hydrous titanic acid, and an oxide or hydroxide of aluminum or titanium is added thereto, followed by heating. The amount of colloidal titanium oxide to be adsorbed is 0.5 of the generated powder.
The range is preferably 80% (by weight), more preferably 1
~50%. When the amount of colloidal titanium oxide adsorbed is less than 0.5%, there is almost no ultraviolet shielding effect;
Furthermore, if 80% or more of colloidal titanium oxide is mixed, the titanium oxide will not be fully adsorbed to the powder, which is not economical.

The average particle size of the colloidal titanium oxide-adsorbed silk pigment of the present invention is usually 0.5 to 100μ, preferably 1
-60μ, particularly preferably 3-30μ. When the average particle size is larger than 100 μm, adhesion to the skin, affinity, spreadability, etc. are not good, and when it is smaller than 0.5 μm, the spreadability is not good.

Next, the method for producing the silk pigment of the present invention will be described. Silk fibroin raw materials to be applied to the present invention include cocoons, raw silk, cocoon scraps, raw silk scraps, bis, fried cotton, silk cloth scraps, boulet, etc., in hot water or enzymatic treatment in the presence of an activator as necessary according to a conventional method. Using scouring silk which has been dried by removing sericin in warm water in the presence of
Although it is dissolved by the method described in Japanese Patent No. 49, an aqueous solution of hydrochloric acid or nitrate of calcium, magnesium, or zinc is preferable as the solvent from the viewpoint of cost and use. The salt concentration of these aqueous solutions varies depending on the type of solvent used, temperature, etc., but the concentration of metal salts etc. is usually 10 to 80% by weight, preferably 20 to 70% by weight, particularly preferably 25 to 60% by weight.
Weight%. Further, it is more preferable that the silk fibroin aqueous solution is subjected to dialysis desalination to completely remove the hydrochloride or nitrate used for dissolving the silk fibroin raw material.

The aqueous silk fibroin solution to be transferred to the coagulation step has a silk fibroin concentration of 3 to 20% by weight, preferably 4 to 15% by weight, particularly preferably 5 to 10% by weight. If the silk fibroin concentration is less than 3% by weight, a uniform gel body will not be produced and the coagulation time will be long, making it uneconomical.
On the other hand, if it exceeds 20% by weight, the gel body becomes hard and it becomes very difficult to remove water from the gel body in the subsequent dehydration step. A titanium oxide sol aqueous solution is mixed with an aqueous silk fibroin solution with an adjusted silk fibroin concentration under stirring, followed by gelation in a coagulation step with or without mixing different pigments, and colloidal titanium oxide is adsorbed.

In the present invention, methods for coagulating and depositing the colloidal titanium oxide-coated silk pigment include mixing a coagulating salt into a mixed aqueous solution, blowing air, isoelectric focusing, ultrasonic treatment, and high shear deformation rate. This is carried out by at least one method such as stirring. When using a coagulating salt, for example, a concentrated aqueous solution of sodium chloride, potassium chloride, sodium sulfate, potassium sulfate, ammonium sulfate, sodium nitrate, potassium nitrate, etc. is mixed and stirred to precipitate silk fibroin gel. The concentration of the coagulating salt in the concentrated aqueous solution is adjusted so that the concentration of the mixed solution with the mixed aqueous solution is usually 5 to 10% by weight. Air is normally blown into 1 liter of mixed aqueous solution.
Usually, air is blown in at a rate of 0.1 l/min or more, and the blowing time varies depending on the amount of air per unit time, but is usually 10 minutes or more. Isoelectric point coagulation is carried out by adding inorganic acids such as hydrochloric acid and sulfuric acid, or organic acids such as acetic acid and citric acid to the mixed aqueous solution while stirring to adjust the pH to 4.0 to 4.5, and then stirring the solution to a pH of 4.0 to 4.5.
Do this for at least a minute. In the ultrasonic treatment, the mixed aqueous solution is placed in an ultrasonic generator, and ultrasonic waves of usually 30 KHz or higher are passed through the solution while stirring, and the process is carried out at room temperature for one hour or more to solidify the silk pigment gel. Silk pigment gel can be precipitated by stirring alone, but in this case it must be done at a high shear deformation rate, and usually 5
The shear deformation rate is 0/sec or more, preferably 100/sec or more. The stirring time varies depending on the concentration of the aqueous solution, shear deformation rate, etc., but gelation is usually achieved in one hour or more.

The silk pigment precipitated in the form of coarse particles with a diameter of about 0.5 to 5 mm is usually 100 to 50% of the solid content.
After centrifugal dehydration to about 0% by weight, subsequent drying can easily bring the material to an absolutely dry state. Drying is
The process is carried out at a temperature of 60 to 120°C under normal pressure or reduced pressure, and then pulverized by using a pulverizer such as a hammer mill or a jet mill, with a particle size of 1 to 100μ, preferably 4 to 80μ, particularly preferably Adjust to 5-30μ. The finely powdered silk pigment produced by the method of the present invention is prepared by dehydration and drying after gelation, and therefore it is thought to have extremely fine pores and has high hygroscopicity and water retention. However, because of this, fine silk pigment powder may have the property of swelling strongly during use. Therefore, in the present invention, it is preferable to subject the obtained silk pigment to a moist heat treatment under saturated steam at a temperature of 50°C or higher, particularly 80 to 120°C. This treatment can be carried out at the stage of powder after dehydration and drying, or at the stage of fine powder after pulverization. Furthermore, before drying, silk fibroin can be prepared by heating in a hot aqueous solution of a neutral salt such as sodium chloride, potassium chloride, sodium sulfate, potassium sulfate, ammonium sulfate, sodium nitrate, etc. at a temperature of 50°C or higher, or an organic solvent such as acetone or alcohol. It is possible to further promote the hot water insolubilization of .

[0018]

[Examples] Examples of the present invention will be described below. The ultraviolet shielding rate was determined by suspending 50 mg of the fine powder in 50 ml of propylene glycol and measuring the ultraviolet transmittance in the range of 190 to 400 nm using a Hitachi Model 557 dual-wavelength spectrophotometer. UV shielding rate (%) = 100 - UV transmittance (%)

0
Example 1 Using silk spinning waste as a raw material for silk fibroin, one of the
00 parts was stirred and refined in a solution of 30 parts of Marcel soap and 3000 parts of water at 95 to 98°C for 3 hours to reduce the remaining glue to 0.1 parts.
%, washed with water and dried with hot air at 80°C. 100 parts of calcium chloride (CaCl2.2H2O) and 100 parts of water were mixed to prepare 200 parts of a 38% by weight calcium chloride aqueous solution and heated to 110°C. 40 parts of scoured silk waste was added to this while stirring using a kneader for 5 minutes, and the mixture was further stirred for 30 minutes to completely dissolve it. Next, 2,000 regenerated cellulose hollow fibers with an inner diameter of 200μ, a membrane thickness of 20μ, and a length of 500mm were bundled together, and a hollow fiber type dialysis device was used in which both ends of the fibers were bundled and fixed (sealed) without blocking the hollow holes. , the solution was added to 0.
Dialysis was performed using deionized water at a rate of 1 liter/hour to obtain a silk fibroin aqueous solution. The fibroin concentration of the aqueous solution was 6.5% (weight), and the residual calcium chloride was 0.001% (weight). While stirring 100 parts of the obtained silk fibroin aqueous solution, 28 parts of a 10% (by weight) titanium oxide sol aqueous solution (manufactured by Catalysts Kasei Kogyo Co., Ltd., trade name: Neosunveil PW-6010) was mixed, and the mixture was stirred at room temperature. Strong stirring was performed using a stirring device with a shear deformation rate of 100/sec until silk fibroin solidified and precipitated (gelatinized). The system at the initial stage of stirring is almost a transparent aqueous solution, but as stirring continues for 2 to 3 hours, silk fibroin gradually coagulates and precipitates into particles.At this stage, 10 parts of ammonium sulfate is mixed, and when stirring is continued, The entire system solidified as a gel. This was washed with water, water removed using a centrifugal dehydrator, and dried at 105°C to obtain 9.3 parts of coarse powder. Based on the yield, the colloidal titanium oxide in the titanium oxide sol aqueous solution is almost 100%.
It can be seen that the titanium oxide was adsorbed onto the silk fibroin gel with a yield of 30% (by weight). The obtained coarse powder was finely pulverized with a jet mill to obtain a colloidal titanium oxide adsorbed silk powder with an average particle size of 10.4 μm. An electron micrograph of the obtained silk powder is shown in FIG. 1, and an ultraviolet shielding spectrum is shown in FIG. Electron micrographs show colloidal titanium oxide adsorbed at high density on silk powder. Furthermore, it can be seen from the ultraviolet shielding spectrum that the ultraviolet shielding effect is also remarkable. Furthermore, the fine powder had extremely good adhesion, spreadability, and feel on the skin, and was suitable as a cosmetic pigment.

Example 2 According to Example 1, silk pigments were obtained by varying the amount of colloidal titanium oxide adsorbed onto silk powder. Table 1 shows its ultraviolet shielding rate at 280 nm and 380 nm and its evaluation as a cosmetic pigment. Note that the adsorption rate refers to the ratio of adsorbed colloidal titanium oxide to mixed colloidal titanium oxide (silk precipitation is assumed to be 100%).

[0021]

[Table 1]

The results show that when the amount of colloidal titanium oxide in the powder is 0.5 to 80% (by weight), the ultraviolet shielding effect is remarkable and it is also very good as a cosmetic pigment.

Example 3 To 100 parts of a silk fibroin aqueous solution (silk fibroin concentration 7.0%) produced according to Example 1, the particle size (longer diameter)
10 parts of 3-5 μm talc and 30 parts of a 10% (by weight) titanium oxide sol aqueous solution (Neosanvert PW-6010) were mixed and stirred at high speed at room temperature to produce a uniformly dispersed suspension. This suspension was strongly stirred using a stirring device with a shear deformation rate of 100/sec until silk fibroin coagulated (gelled) and precipitated. Stirring was continued for 2 to 3 hours, and at the stage when silk fibroin coagulated and precipitated into particles with talc as a core coating, 10 parts of ammonium sulfate was mixed, and stirring was continued to solidify the entire system as a gel-like substance. This was washed with water, water removed using a centrifugal dehydrator, and dried at 105°C to obtain 19.8 parts of coarse powder. It can be seen from the yield that colloidal titanium oxide in the aqueous titanium oxide sol solution was adsorbed onto the talc-coated silk fibroin gel with a yield of approximately 100%. The obtained coarse powder was finely pulverized with a jet mill to obtain a colloidal titanium oxide adsorbed silk pigment with an average particle size of 6.6 μm. The UV shielding rate of this product is 92% at 280 nm and 380 nm.
At 60%, the shielding effect was significant. Furthermore, the fine powder had extremely good adhesion, spreadability, and feel on the skin, and was suitable as a cosmetic pigment.

Example 4 According to Example 3, the amount of titanium oxide in the titanium oxide sol was fixed at 5% (weight) of the total solid content, and the mixing ratio of silk and talc was varied to obtain a silk pigment. Table 2 shows the ultraviolet shielding rate of the obtained silk pigment at 280 nm and 380 nm and its evaluation as a cosmetic pigment.

[0025]

[Table 2]

The results show that the colloidal titanium oxide-adsorbing silk pigment has a remarkable UV-shielding effect when the proportion of talc, which is a different pigment to be combined, is 80% (by weight) or less, and it is extremely good as a cosmetic pigment. be. When the content of different pigments in the silk pigment exceeds 80%, the proportion of silk inevitably decreases, and the adsorption amount of colloidal titanium oxide becomes extremely poor, making it impractical.

Example 5 According to Example 4, the amount of colloidal titanium oxide adsorbed on 50% (weight) of silk fibroin was 10% (weight), and the amount of different pigments to be composited was changed to 40% (weight) as shown in Table 3. A silk pigment was produced. Two of these silk pigments
Table 3 shows the ultraviolet shielding rate at 80 nm and 380 nm and the evaluation as a cosmetic pigment.

[0028]

[Table 3]

As described above, the colloidal titanium oxide adsorbed silk pigment of the present invention has a remarkable ultraviolet shielding effect and is also good as a cosmetic pigment.

[0030]

Effects of the Invention The colloidal titanium oxide-adsorbing silk pigment of the present invention is capable of adsorbing a large amount of colloidal titanium oxide and has an excellent ultraviolet shielding effect. Furthermore, it has good adhesion, spreadability, and feel to the skin, and also has excellent moisturizing properties, hiding properties, dispersibility, miscibility, balance between hydrophilicity and lipophilicity, and skin protection properties. The silk pigment of the present invention is extremely useful for applications such as cosmetics, food, and paints, and the method for producing it is industrially advantageous.

[Brief explanation of the drawing]

FIG. 1 is an electron micrograph showing the structure of silk pigment particles adsorbed with 30% by weight of colloidal titanium oxide obtained in Example 1 of the present invention.

FIG. 2 is an ultraviolet shielding spectrum of the silk pigment similarly obtained in Example 1.

Claims (2)

[Claims] 1. A silk pigment characterized in that colloidal titanium oxide is adsorbed to a base pigment of silk powder or a composite pigment of silk powder and a different pigment. Claim 2: A titanium oxide sol is mixed with an aqueous silk fibroin solution obtained by dissolving silk fibers, and then a different pigment is mixed or not, and then a coagulating salt is mixed, air is blown, and an isoelectric treatment is carried out. The colloidal titanium oxide according to claim 1, characterized in that the particles are coagulated and precipitated by at least one treatment such as point solidification, ultrasonication, and stirring at a high shear deformation rate, and then washed with water, dried, and pulverized. Method for producing adsorbed silk pigments.